Field of the Invention
The embodiments of the present invention relate generally to a device for a patient-specific acetabular reaming and cup positioning guide. In particular, the embodiments of the present invention are directed to a device that includes a patient-specific guide and template for use in total hip arthroplasty surgeries.
Background
Total Hip Arthroplasty (“THA”) is a complex orthopedic operation in which surgeons replace a diseased hip joint with implants. THA is commonly performed to relieve joint pain and improve quality of life. Approximately 200,000 THA surgeries are performed each year in the United States, and the number is likely to reach 570,000 by the year 2030. The current costs of THA surgery is approximately $25,000.
A rising percentage of patient research information about THA surgical technologies and surgeons before making the final decision regarding surgery. As a result, the THA market is driven by well-educated patients and their demand for technological advances, which further drives the need for improved acetabular reaming and positioning guides, and devices directed to the same.
As shown in FIGS. 11-13, which are explained in further detail below, the acetabulum is the socket of the hip bone, into which the head of the femur fits. It is essentially a concave cavity that receives the femoral head, where the femoral head is able to move (i.e., the ball shaped head on the top of the femur is able to rotate around in the concave cavity forming a “ball and socket” joint). Reaming is a process in which surgeons use a reamer to remove diseased bone and cartilage. Reaming also determines the correct size and position of the socket in preparation for the placement of acetabular component.
Properly reaming the acetabular socket and placing the implant in a suitable position and orientation is critical for the success of a THA surgery. Inaccurate implant placement can contribute to various complications such as bearing surface wear, implant dislocation, limb length discrepancy, component impingement, osteolysis, implant loosening, and premature or early failure. These complications can lead to hospital readmission and revision surgery, and can result in a poor clinical outcome and significantly increase healthcare costs.
Acetabular socket reaming and implant placement is a complicated and time consuming procedure. In currently available surgical techniques, the dominant method is the traditional freehand method that involves making a 4 to 8 inch incision on the side of the hip. The clinical outcome relies heavily on the surgeon's experience and onsite execution. Because the socket is deep within the incision and surrounded by muscles, fat, and other soft tissues, it is difficult for even well-experienced and high-volume surgeons to consistently attain correct acetabular component orientation and position, especially for high body mass index (“BMI”) patients. Minimally invasive surgery (“MIS”) allows the surgeon to perform the THA surgery through a smaller incision (approximately 3 to 6 inch). MIS incision candidates are typically thinner, younger, healthier, and more motivated to have a quick recovery and shorter hospital stay. However, MIS has not shown any better long-term clinical outcomes than traditional THA surgery. Its learning curve is long and it is easier for new surgeons to make mistakes due to limited vision of the surgical site.
Image-guided navigation surgery uses computer surgical planning to determine the implant size and alignment preoperatively. The surgery is executed with the help of intraoperative implant registration instruments. The surgery can achieve high accuracy and consistency, but the application has been jeopardized by high instrument costs, long operative time, and a steep learning curve.
Use of patient-specific surgical guides/templates is a relatively new technique and has been used in the installation of dental implants. It is usually designed in a computer surgical planning procedure based on a patient's bone geometry (three-dimensional reconstruction of CT or MRI images) and then manufactured using medical grade plastic materials. The template can be fixed onto a unique area of the bone and includes a structure that can guide surgical tools through certain locations and directions to remove bone with precision and place implants with proper orientation consistently. The computer surgical plan is usually approved by a surgeon and if properly designed and executed, the guide will help the surgeon replicate the plan in patients to achieve optimal implant position and orientation. In recent years, surgical guides are becoming more common in orthopedic surgeries. An example of a custom-fit surgical guide for total knee arthroplasty (“TKA”) can be found in U.S. Patent Application Publication No. 2010/0049195 to Park et al., entitled “Arthroplasty System and Related Methods.” Due to successful clinical outcomes, similar surgical guides have been used by more and more surgeons to replace the costly navigation guided TKA surgery and reduce operative time.
In the case of acetabular reaming and positioning guides current techniques have various limitations. For example in the guide described in U.S. Patent Application Publication No. US 2012/0041445, the cylinder may be too big and can impinge with the femur even when the femoral head/neck is removed, resulting in the guide not sitting in the intended position to achieve accurate reaming. Another issue is that the three legs are too long. The surgeon will need to remove significant amounts of the soft tissue around the acetabular rim to allow the legs to sit at the right locations. If this soft tissue is not removed, inaccurate location of the three legs will change the orientation and location of the reamer and eventually influence the accuracy of the implant placement. The same issue exists in the guide disclosed in International Patent Application Publication No. WO 2012/010366, wherein the three legs require large soft tissue cuts and may lead to inaccurate reamer orientation and positioning. In addition, the reamer and its connected guide part are not designed for easy installation, which is required during the surgery to change reamers and remove bone.
There is currently a need for an improved THA surgical guide in the medical device market. Specifically, there exists a need for a patient-specific guide/template for both surgeons and patients of THA. The embodiments of the present invention properly solve the problems of the prior art.